Lamp socket having leaf spring contacts



April 17, 1951 A. J. sHABAcK v $49,134

LAMP SOCKET HAVING LEAF SPRING CONTACTS Filed Dec. 15, 1947 @l @e 2" l 2 Sheets-Sheet l v; ,7 26 ATTORNEY April 17, 1951 A. J. SHABACK 2,549,134

I LAMP SOCKET HAVING LEAF' SPRING CONTACTS Filed Dec. l5, 1947 2 Sheets-Sheet 2 INVENTOR. ANDREW J. SHABAcw Y EXW ATTORNEY' Patented Apr. 17, 1951 LARIP SDCKET HAVING LEAF SPRING `CONTACTS Andrew J. Shaback, Philadelphia,`1a., assigner to Electric `Service ManufacturingtCo., Philadelphia, Pa.,V a corporation of Pennsylvania ,Application December 15, 1947,-Serial.No791,895

7 Claims. 1

Thisinvention relates to electric 'lamp sockets `and more `particularly to mprovementsin the design and construction of that type of automotiv'esocket commonly employed for receiving the bayonet type base of lamp.

Among the principalobjects of the present invention is to provide alamp socket having a `contact 'elementfof `such form `and construction and so operatively mounted in the socket that the delection thereof during normal operation of 'the socket is at all times Amaintainedbelow `the proportional limit of the'metal of which .the contact element is formed. Tothis end, the contact '.element of the'present socket is in the vform of ,a relatively long leaf spring .constructed of suitable spring'ma'terial andso anchored in the socket as to ,provide a iiexing fulcrum for the element which is well removed from the zone of contact of the lamp terminal therewith,therebypreventing any vpossibility of the `leaf spring developing Aa permanent Vset under repeated exing thereof.

`More specicallynt is an important object of the present invention toprovide aso'cket `having leaf spring contacts respectively inter-poseddb rectly between the lamp terminals andthe `conductors supplying current thereto wherein-each leaf spring "is "anchored yin such manner as to provide'an extraordinarilyllong lever rarmfor the terminal endthereof whereby to reduce thebending moment and resultingstre'ss of theleaf spring at its fulcrum point while at the same i time providing adequate movement .thereofat its lamp Contact end.

More generally, Ait is an object 'off the present invention `to provide'a lamp socket ofthe type aforesaidwherein the conventional axially movable spring-pressed contacts are replaced by simple leaf yspring elements having means formed Vintegrally therewith for securely anchoring the same upon an insulating body fitted within the socket shell, the said insulating body 'and the leaf "spring lelements being Aso complementally formed as vto insure *that the `required deection of the"1eaf\spring elementsunder pressure exerted thereon `bythe base of 'the lamp inserted in the socket is at all times well below the proportional limit of the :leaf spring material.

A further object of therpresent invention is to Y provide a lamp Vsocket which is simple in conn struction, economical of manufacture 'and which includes an easily assembled twoepart insulating body which may be employed without structural modification for supporting either a` pair of `leaf springs to adapt the socket for use `with a doublecontactlamp or a simpleleaf `spring 'to adopt it for usefasfa single-contact lamp socket,

-Other objectsY and advantages of the present invention will appearmore `fully hereinafter, Lit being understood that said invention consists substantially vin the combination, construction, location and relative arrangement of the parts, all as described in'detailfhereinafter,.as Ishown in the accompanying drawings and as ,finally pointed out initheappended claims,

In the accompanying drawings which "illustrate a preferred embodiment of the` present invention,

Figure -l 'is a View, partially in vertical section, cfa socket constructed in accordance with 'the present invention, saidvi'ew being asltaken along the line I-I of Figure 2;

"FigureZ is a vertical sectional view Aifthe socket as taken `along the line`^2i2 ofFigure l;

Figure? isa'vertical sectionalviews'imilar to Figurel but showing'the leaispring contactelementsthereof intheir relaxed condition,` as when thelamp is completely removed from'the socket;

Figure 4 is 'an end view ofthe socket as viewed from the line 4-'4 of Figure 3;

*Figure 5 is a transverse sectional View as taken along the line 5-5 `of Figure ,3;

,Figure is an end viewas viewed fromtheline G-SiofFigure'S; 1

:Figure 'TI 'isla 'bottom view "of the socket as 'viewedfrom line' 1-1 of Figure 3;

'Figure *8 is an 'exploded'viewfshowing in ,separated relation` all of'the several Aelements fof :the socket except the leaf'fspring contact elementsi Figure 9 is another exploded view Atakenat right anglestoligure Sshowing in separatedrelation allof the several elements of Athe socket including the leaf Vspring contact telementsthereof;

Figure .'10 is a side elevational view'of .a `leaf spring 'contact element vias viewed from the line lil-1B of Figure 9;

Figure 11 is a plan View of the insulating plug assembly asviewedfrom II-IIrof Figure 9;

Figure 12 is a plan wview of the blankof which the 4socketshell is formed;

'Figure 1-3'is a view ofmodied form of the leaf spring 11 contact element;

Figure 14 is a view corresponding "toiFigureS showingthe socket fitted with a` single' leaf spring contact of-theform shown in Figure 13; j

Figure 15 is avertical sectionalview Aas `taken along'the line 15;115 of Figurelfi; and

`Figure"-16 isa bottom view'of `the ,singlecontact `socket as viewed along vthe line IB- IG 'of Figure 14.

Referring 'now' more particularly ,to the drawi ings, it will Abe t observed that" the socket 'of the present invention includes an outer metallic cylindrical shell I of more or less conventional type formed of a single blank of sheet metal shown in Figure 12 and suitably stamped to provide a pair of diametrically opposed bayonet slots II-II formed in the portion thereof which receives the base of a lamp (shown dotted in Figures 1 and 2), this 4base being conventionally provided with opposed pins (not shown) respectively engageable within the bayonet slots to secure the lamp Within the socket.

Snugly fitted Within the inner end portion of the socket shell I0 is an insulating body I2 serving as a support or mounting for a pair of leaf spring contactJ elements I3-I3, said insulating body being formed of a pairV of semi-cylindrical members I2=1lI2a separable from each other along a diametrical plane I4. The members I2-I 2a are commonly bored, as at I5, normal to the plane of their separation, this bore I5 being fitted with a spring-pressed detent I6 having a reduced outer end Il which projects through an opening I3 suitably provided in the Wall of the cylindrical shell I0. A coiled compression spring I9 interposed between the detent I6 and the opposite Wall of the shell I imparts a normal outward bias upon the detent I6, which thus serves conjointly with a struck-in tab 20a engageable in the opposite end of the plug bore I5 to retain the insulating body I2 within the lamp socket shell I0, the detent I6 serving further to removably mount the socket assembly Within a suitable support therefor such as is shovvn in dotted line representation in Figures 1 to 4.

As appears most clearly in Figures l, 2, 9 and 10, the leaf spring contact elements I3-I3l are of identical form and construction, each being formed of suitable springly material, such as phosphor bronze, nickel silver, steel or the like, to provide a bifurcated, flat body portion 26 terminating at one end thereof in a looped portion 2| adapted to frictionally receive a suitable terminal plug secured to the end of a conductor wire', such plug being conventional in the art and being represented in Figure 4 by the dotted line element designated 221. The bifurcated main body portion 26 of each contact element I3 includesa pair of laterally spaced legs 22 and 23 of unequal length, the longer leg 22 being provided with an extension 24 forming an obtuse angle with the leg 22. The shorter leg 23 is alsopro- 4 clearly in Figure 9. The lower extremity of the inner Wall of the groove 26 is rounded off, preferably, as at 28.

The effective length of the grooves 26 formed in each of the members I2a is slightly less than the length of the normally `ilatfor undeiiected body portion of the leaf spring -contact terminal I3, While the effective depth of each of said grooves is approximately equal to one-half the Width of said body portion of the contact element. In the case of the notches 2`I, they are of Y a-size and shape to snugly accommodate therein vided with an extension 25 bent Vsubstantially at Y rightang'les to the leg 23. It will be noted that the extensions 24 and 25 are both bent in the same general -direction relatively to their respective supporting legs 22 and 23 and that the longer extension 24 is spaced from the shorter extension 25 both laterally and longitudinally of the main body portion 20 of the leaf spring contact.

` The complemental semi-cylindrical parts I2i-I2a forming the insulating body I2 in Which are operatively mounted the Contact elements I3-I3 are each provided in the inner ilat face thereof vvith a groove 26 extending long-itudinally of the plug and With a right angle notch 21 spaced laterally from the groove 26, the groove 2,6 and the notch 2'I being thus disposed to either side of the vertical central axis of the insulating body I2. The groove 26 of each member I 2a is of gradually increasing Width so that the inner end` thereof is of enlarged width, this gradual increase in effective Width of the groove 21 being obtained by tapering the inner Wall of this groove relatively to its outer wall, all as appears most terminals the short leg of the leaf spring and its right angular extension 25, these notches 2'I being also of depth approximately equal to one-half the overall Width of the contact element I3. The positional relation of the grove 26 and notch 21 in each of the plug parts IZa-I 2a is such that when these parts are assembled to form the cylindrical body I2 for insertion into the rear or outer end of the socket shell I0, the grooves 26-26 of said members I2a are respectively in registery with the notches 2'I-2'I thereof. Thus, the cylindrical insulating body I2, when properly fitted Within the socket shell I0, is provided with a pair of laterally spaced recesses, each of which extends transversely across the diametric plane I4 of the insulating body, one-half of each recess, disposed in one of the plug parts I2a, beingI of tapered cross-section having its larger end presenting inwardly of the socket shell and the other half, disposed in the opposite plug part, being of right angular form. 'Ihe tapered halves of the recesses extending vertically through the insulating body I2 are disposed on opposite sides of the diametric plane I4 of said body, said halves being thus located in diametrically spaced quadrants of the cylindrical body, as see Figure 11.

The contact terminals I3 are respectively disposed within the insulating body I2 so that While the short leg portion 23 of each such element is accommodate within the notch 21 of one of the insulating body members I2a, the longer leg 22 of the other contact terminal is accommodated within the tapered groove 26 of said contact member I2a. In other Words, the mounting of the contact terminal I3-'I3 Within the insulating body I2 is such that the short legs 23-23 of the terminalsI respectively t in the notches 2'I-2l of the insulating body, While the longer legs 22-22 respectively t in the tapered grooves 26-26 of the insulating body. When so assembled Within the insulating body, the contact therefrom by reason of the fact that the inturned flanges 25 at the lower ends of the short legs 23-23 are respectivelylodged in the Iaterally extending portions of the notches 21-21, thereby securing the terminals I3-I3 against vertical displacement from the insulating body. In thisl secured condition of the parts, Vthe-extensions 24-24 of the Contact terminals I3- I3 are disposed in laterally spaced relation, the contact elements I3-I3 being completely insulated from each other.

In order to most expeditiously eiect assembly of the Contact elements I3 within the insulating body I2 prior to insertion of the latter into the rear end of the socket shell I0, each of the elements I3 is mounted in one of the complementally formed semi-cylindrical members I2a by inserting the short leg 23 .of the terminal laterally into the notch 2'I of the member I2a. The longer leg` 22 of the contact element and its angularly bent extension 24 Will `then be disposed externally of I3-I3 are secured against removal Y einen e4 pin 29 of one part being ente'redinto the-register- Sing recess of the other part "Lto insure that the said .plug partslare in axial coincidence for proper insertion into `and retention by the socketishell il).

l As most clearly-appearsfinFigures1.andff3, the

terminal elements Isa-I3 eachprovides ajdirect alsingle connection between the terminal oil allamp received in the socket andthe conductor for supplying currenttolsaid lamp terminal. Further, and more importantly, it will be observed that in the lamp socket vof the construction just 4rdescribed each contact-terminal 'i3 lthereof is -provided with a leaf springportion formed oi the leg 22 and its angularly bent extension 2d, the leg portion 22 being free'for flexingmovement within the limits provided therefor lby its accommodating tapered -groovev 26. It will be noted in this connection .thatinits normal ``unflexed condition each legportionf22 ofthe'contact terminals l3-i3 is disposed vin coplanar Irelation `with respect to thewanchoringhleg "23rof the contact terminals, as shown in 'Figure `3. However, when a lamp is inserted into the socket so as to present its terminals in engagement with the extensions 2li-24 of the legs 22-22 of the contact terminals, said legs are each flexed into a position as shown in Figure l, suchviiexure occurring about a fulcrum 3l located at the base of the leaf spring immediately adjacent the looped end portion thereof.

Because of the relatively long character of the leaf spring contact elements l3-i3 employed in the socket of the present invention, aiiording as they do primary flexing at the fulcrum points 3I-3I, it becomes possible to limit deflection of the leaf spring Contact to a degree insuring that the stress to which the leaf spring is subjected during normal operation of the socket is at all times well below the proportional limit of the spring material of which the leaf spring is formed. Thus, in the socket of the present invention, the leaf spring contact members do not acquire a permanent set under continued flexing thereof, in consequence of which the life of the socket is materially prolonged.

In the socket construction of the present invention the anchoring extremity of the leg 23 of each contact element is so disposed inwardly of the end surface of the insulating body I2 and insulatingly encased by the, plug body that the possibility of inadvertently short-circuiting the contact members I3 through engagement of the extension 24 of one of said elements with theanchoring extremity 25 of the other of said elements is entirely eliminated.

Figures 13 to 16, inclusive, show a modied construction of the socket wherein a single leaf spring contact element 32 is employed to adapt the socket for use with a lamp of the type having a single contact centered in the end of the lamp base. Except for this contact element 32, the socket of Figures 13 to 16 is identical in construction with that of Figures 1 to 11, the twopart plug thereof being employed to support the single leaf spring element 32 instead of the pair of laterallyspaced elements I3-l3.

Obviously,

6 'this list/"a decided fadvanta'ge in Tthe manufacture of the socket inasmuchas the plugiparts, 'socket -s'li'ell and spring-pressed `detent 4may f'be "inter- 'c'ha'ngeably employed in the construction; of

single or double contact-types of so'ckets.

The leaf spring ccntactfelement 32 necessarily diiers somewhat in construction "from the elenments |3-'-| 3 in that lits lamp-engaging 'end 33 `extends laterally of the flexing leg portion 22a 4thereof for properengagement with the single lamp contact centered in the `lbasefof thelalnp. `As-in the case of the contact elements I3-"l3,fthe lsingle type leaf springelem'ent 32 is provided with ja short anchoring leg portion 23SL having `a right angular extension 25a which is received 'within ithenotch 2l of one 'ef theplug parts 12e, `fw'liil'e thef-legportion 22a is disposedwthinthe tapered groove -lzs'in thecther of saidplug parts fe'rfnexlingfab'o'ut a 'fulcrum pointl3l a.

' `It will be understood,l of course, th'atithefpre'sent `invention is susceptible of various 4changes-"and lm'odiiications which may be made from time to -ltiine"without departing from the `gen'eralp'rinnciples and real spirit thereof and it is, accordingly, intended to claim thesame broadly aswell las specifically, as indicated in the appended claims.

What is claimed as new and useful is:

`1. ln alampsocket ofthecharacter described, `@al'cylindrical lamp-receiving shell, a plug of elec'- itrical insulatingmaterial fitted-in onefend of said 'snel-l, said plug havinga' tapered recess *spaced laterally of the longitudinal axis of the plug and extending longitudinally therethrough with its enlarged end opening into said shelLand a leafspring contact element disposed in said recess and anchored in said plug for flexing movement about a fulcrum located in the immediate region of the reduced end of the recess, said element having a freely extending lamp-engaging portion disposed externally of the enlarged end of said recess and bent angularly with respect to the portion of the element disposed in said recess.

2. In a lamp socket of the character dei-ined in claim 1 wherein said leaf-spring contact element includes an integral part adapted for interlocking engagement with said plug to prevent longitudinal displacement of said element from said plug.

3. In a lamp socket of the character defined in claim 1 wherein said plug includes a pair of said tapered recesses respectively disposed to either side of the longitudinal axis of the plug, and wherein each of said recesses is fitted with one of said leaf-spring contact elements, the freely extending portions of the latter being disposed in crossed relation externally of the plug and being spaced to either side of the longitudinal axis of the plug.

4. In a lamp socket of the character described, a cylindrical lamp-receiving shell, a plug assembly of insulating material fitted in one end of said shell, said plug comprising a pair of complementally formed semi-cylindrical parts adapted for assembly with the dat sides thereof disposed in a common plane extending diametrically of the shell, each of said plug parts being provided with a tapered groove extending lengthwise thereof and with a notch, said groove and notch being disposed to either side of the longitudinally extending median plane of said plugl part, and Ia pair of leaf-spring contact elements bound in spaced relation between said assembled plug parts, each of said elements including co-planar portionsrespectively disposed edgewise in the tapered groove of oneplug part and inthe notch of the other plug part.

bly of insulating material tted in one end of said shell, said plug comprising a pair of complementally formed semi-cylindrical parts adapted for assembly with the fiat sides thereof disposed in substantial coincidence with a plane extending diametrically of said shell, each of said plug parts being provided with a pair of recesses formed in the flat face thereof and spacedV to either side of the longitudinally extending median plane of the assembled plug parts, at least one of said pair of recesses extending the full length of the assembled plug parts and the recesses of one plug part being adapted for respective registry with those of the other plug part the pair of recesses extending the full length of the plug parts being each longitudinally tapered and disposed with its enlarged end opening into said lampreceiving shell, and a leaf-spring contact element confined between the assembled plug parts vwith one portion thereof disposed edgewise in the recess extending the full length of one of said plug parts and a second portion thereof disposed in the registering recess of the other plug part; the portion of said element disposed in said fulllength recess being adapted for flexing movement about a fulcrum located in the immediate region o'f the outer end of said plug assembly and having an angularly bent extension at the inner end ofsaid plug assembly proj ectingtransversely across the plane of separation of said plug parts.

6. In a socket ofthe character dened-in claim 5 wherein the recess in registry withsaid fulllength recess is formed with an angular extension and wherein said second portion of the leaf-spring element is provided with a complementally shaped angular extension to secure thei element against longitudinal displacement with respect to the plug assembly.

REFERENCES CITED The following references are of record in the ile of this patent:

UNITED STATES PATENTS Number Nam'e Date 1,085,960 Berg Feb. 3, 1914 1,383,764 Sargent July 5, 1921 1,664,403 Douglas Apr. 3, 1928 2,036,366 Shore Apr, 7, 1936 2,169,219 Brownstein Aug. 15, 1939 2,254,754

Reece Sept. 2, 1941 

